6r^2-12r-18=0

Solution for 6r^2-12r-18=0 equation:

6r^2-12r-18=0

a = 6; b = -12; c = -18;
Δ = b2-4ac
Δ = -122-4·6·(-18)
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-24}{2*6}=\frac{-12}{12}
=-1
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+24}{2*6}=\frac{36}{12}
=3
$